Pneumatically damped relay

ABSTRACT

The invention relates to a relay ( 16 ), especially for electrical starting devices for internal combustion engines. The relay ( 16 ) comprises a relay armature ( 168 ) and an armature return element ( 171 ). A fluid, enclosed in a hollow space ( 236 , Δs), between the relay armature ( 168 ) and the armature return element ( 171 ) pneumatically damps the collision between the relay armature ( 168 ) and the armature return element ( 171 ).

BACKGROUND OF THE INVENTION

DE 101 24 506 A1 relates to a starter for a motor vehicle. The startercomprises a pole housing which contains the starter motor, an engagementrelay which is arranged parallel to said pole housing and contains asolenoid switch, an engagement lever, which is rotatably mounted with atransition region between the pole housing and the engagement relay, forcoupling the starter motor to the internal combustion engine. A seal toprevent the ingress of contaminants and moisture into the engagementrelay is also provided. The seal is formed by a rubber diaphragm, whichis connected to the housing walls, within the transition region betweenthe pole housing and the engagement relay.

DE 195 49 179 A1 relates to an engagement relay for a starter apparatus.The engagement relay comprises a contact bridge which bridges at leasttwo contact pins in the switched-on state and which is fitted to amoving switching spindle. The contact bridge has in each case at leasttwo defined contact areas which are associated with one contact pin andwhich are provided on spring arms which are flexible in theirlongitudinal extent and transverse to their longitudinal extent.

Whereas approximately 40 000 starting processes are completed over theservice life of a vehicle in conventional electrical startingapparatuses for internal combustion engines, up to half a million andmore switching processes are carried out in starters which are employedin internal combustion engines with a start/stop functionality. Thismeans that the electrical starting apparatus has to be correspondinglydesigned.

The electrical starting apparatus accordingly has to be designed forsuch a high number of switching cycles and complete these withoutproblems. It has been found that relatively high demands are made of theacoustics of the electrical starting apparatus in passenger cars whichare equipped with a start/stop functionality. Noises which are producedby metal elements being struck in the components of a starter, inparticular an electrical starting apparatus, are found to causediscomfort and to be disturbing.

SUMMARY OF THE INVENTION

In order to reduce the noise level when operating an electrical startingapparatus, the invention proposes pneumatically providing pneumaticdamping between components which move relative to one another, inparticular a linearly moving relay armature and an armature return. Whenpower is supplied to the magnet coils of the relay of an electricalstarting apparatus, the relay armature which is displaceably guided inthe relay housing moves toward an armature return which is arranged in astationary manner in the relay. Both the end faces of the relay armaturewhich moves relative to the armature return and those of the armaturereturn have a mutually complementary geometric contour and form a hollowspace which is filled with a fluid, in particular air.

By virtue of providing suitable sealing measures, for example providinga V-shaped sealing lip or a sealing ring which is fitted to the casingsurface of the relay armature which moves relative to the relay housing,the volume of fluid which remains in the hollow space between the relayarmature and the armature return is sealed off to prevent losses, thatis to say leakage, and therefore the volume of fluid can be used as afluid cushion for damping the stopping movement of the end face of therelay armature against the corresponding end face of the armaturereturn, it being possible for this to be used to drastically reduce themomentum of the moving relay armature and accordingly to reduce itsenergy. Examples of a fluid are air or another gas and also a liquid.The volume of fluid remaining in the hollow space between the end faceof the relay armature and the correspondingly designed end face of thearmature return forms a fluid cushion which damps the stopping movementof the end face of the relay armature as it moves into the relay housingand accordingly damps the striking movement, which is produced whencontact is made between the end face of the relay armature and the endface of the armature return, by virtue of a reduction in energy.

The denser the volume of fluid within the hollow space between the endface of the relay armature and the end face of the armature return canbe kept, the greater the damping effect that can be achieved with thesolution proposed according to the invention on account of the lowleakage losses. Instead of the V seal between the circumference of therelay armature and the relay housing, it is also possible to form aprecise transition fit, for example a H7/g6 fit, in order to keep theleakage losses, that is to say the flow of fluid out of the hollow spacebetween the end faces of the relay armature and the armature return, aslow as possible.

In a further variant embodiment for the pneumatic damping of a relay asproposed according to the invention, in particular for operating or forinitializing an electrical starting apparatus, the relay armature cancontain a longitudinal bore. Said longitudinal bore is connected both tothe hollow space between the end face of the relay armature and to thesurrounding area. Furthermore, a longitudinal bore, which issues intothe hollow space between the end face of the relay armature and the endface of the armature return at one end and into a relief space in therelay housing at the other end, likewise extends through the thicknessof the armature return. A valve, for example a non-return valve, can beincorporated in this channel which connects the hollow space to therelief space. If the valve is in the form of a non-return valve, forexample, it is oriented in such a way that it closes when the volume offluid within the hollow space between the end faces of the relayarmature and armature return is compressed, and thereby prevents avolume of fluid from flowing out of this hollow space. In one possiblevariant embodiment of the solution proposed according to the invention,when a valve is provided in the armature return, a main channel, whichcan be closed by a valve element, and an auxiliary channel, which issuesnext to the closing element and is always open, for example, issue atthe valve seat of said valve. The flow cross sections of the mainchannel and the auxiliary channel preferably have a size such that theflow cross section of the main channel is larger than the flow crosssection of the auxiliary channel. If the volume of fluid in the hollowspace between the end face of the relay armature and the end face of thearmature return is compressed, the closing element is pushed into theseat and closes the main channel. In accordance with the design of theflow cross section of the auxiliary channel which stays open, the volumeof fluid flows out of the hollow space between the end face of the relayarmature and the end face of the armature return in a throttled manner,and therefore a volume of fluid which damps the stopping movement of theend face of the relay armature against the end face of the armaturereturn is maintained in the hollow space, this being only partiallyrelieved of pressure into the relief space by means of the auxiliarychannel which serves as an outflow channel when the volume of fluid iscompressed.

In a further variant embodiment of the solution proposed according tothe invention for the pneumatic damping of the relay armature andarmature return, by way of example, a guide bush which surrounds aswitching pin can be provided with a number of openings, for exampletransverse bores. These transverse bores allow, depending on the degreeof opening of said transverse bores, the volume of fluid to flow out viathe openings, depending on the degree of opening of said openings, inthe event of a relative displacement with respect to the armature returnwhich is arranged in the relay in a stationary manner. The guide bushserves, depending on the operating path of the switching pin, as aslide, with the volume of fluid flowing out of the hollow space betweenthe relay armature and the armature return of the relay being defined bythe degree of opening or degree of overlap of the openings which areformed in the wall filling bush. The volume which flows out of thehollow space between the relay armature and the armature return via theopenings in the wall of the guide bush flows into the relief space inthe relay.

In a further variant embodiment of the solution proposed according tothe invention, when a specific travel movement, that is to say aspecific distance ΔS between the end face of the relay armature and theend face of the armature return which is arranged in the relay in astationary manner, is achieved, a valve can be operated by the end faceof the relay armature itself. To this end, a peg-like valve element isprovided in the armature return, said valve element being prestressed bymeans of a spring and being in the closed state as the end face of therelay armature approaches. If the end face of the approaching relayarmature strikes an end of the peg-like valve when the distance Δs isreached, said valve is opened as the relay armature gets closer, andtherefore fluid flows out of the hollow space, which is defined by thedistance Δs, between the end face of the relay armature and the end faceof the armature return, which is accommodated in the relay in astationary manner, only when the distance Δs is reached, and acounterpressure is built up and maintained in order to reach thedistance Δs, said counterpressure counteracting the stopping movement ofthe end face of the relay armature against the end face of the armaturereturn of the relay in a damping manner.

A channel in which the peg-like valve element in the armature return isaccommodated can preferably be formed in such a way that said channel isconnected to a slot by means of which a volume of fluid flows out of theremaining hollow space, which is defined in accordance with the distanceΔs, between the end face of the relay armature and the end face of thearmature return when the peg-like valve element is operated by the endsurface of the relay armature.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be described in greater detail below with referenceto the drawing, in which:

FIG. 1 shows a longitudinal section through a starting apparatus,

FIG. 2 shows a schematic illustration of the relay having a relayarmature and an armature return,

FIG. 3 shows a variant embodiment of a valve in the form of a non-returnvalve,

FIG. 4 shows a guide bush, which acts as slide, in the armature return,accommodated on a switching pin which is not illustrated in FIG. 4,

FIG. 5 shows a V lip formed in a circumferential slot in the relayarmature,

FIG. 6 shows a valve which is operated when a distance Δs is reachedbetween the end face of the relay armature and the end face of thearmature return which is arranged in the relay armature in a stationarymanner, and

FIG. 6.1 shows a section through a channel having a slot in the armaturereturn of the relay.

DETAILED DESCRIPTION

FIG. 1 shows a starting apparatus 10. This starting apparatus 10 has,for example, a starter motor 13 and a relay 16. The starter motor 13 andthe relay 16 are attached to a common drive end plate 19. The startermotor 13 has the functional task of driving a starter pinion 22 which isgenerally in the form of a spur gear. The starter pinion 22 meshes witha ring gear 25 of an internal combustion engine, which is notillustrated in FIG. 1.

The starter motor 13 has, as a housing, a pole tube 28 which has poleshoes 31 on its inner circumference, with a field winding 34 being woundaround each of said pole shoes. The pole shoes 31 in turn surround anarmature 37, which has an armature stack 43 comprising laminations 40and an armature winding 49 arranged in slots 46. The armature stack 43is pressed onto a drive shaft 44. Furthermore, a commutator 52 is fittedat that end of the drive shaft 44 which is remote from the starterpinion 22, said commutator comprising, inter alia, individual commutatorlaminations 55. The commutator laminations 55 are electrically connectedto the armature winding 49, in a known manner, in such a way that, whenpower is supplied to the commutator laminations 55 by carbon brushes 58,a rotary movement of the armature 37 is produced in the pole tube 28. Apower supply line 61 which is arranged between the meshing relay 16 andthe starter motor 13 supplies power to both the carbon brushes 58 andthe field winding 34 in the switched-on state. The drive shaft 44 issupported on the commutator side by a shaft journal 64 and a slidingbearing 67 which in turn is held fixed in position by a commutatorbearing cap 70. The commutator cap 70 is in turn fixed in the drive endplate 19 by means of tension rods 73, which are arranged distributedover the circumference of the pole tube 28 (screws, for example two,three or four pieces). In the process, the pole tube 28 is supported onthe drive end plate 19, and the commutator bearing cap 70 is supportedon the pole tube 28.

In the drive direction, the armature 37 is adjoined by a sun gear 80,which is part of a planetary gear mechanism 83. The sun gear 80 issurrounded by a plurality of planet gears 86, usually three planet gears86, which are supported by means of roller bearings 89 on axle journals92. The planet gears 86 roll in a hollow wheel 95, which is mountedexternally in the pole tube 28. In the direction toward the output driveside, the planet gears 86 are adjoined by a planet carrier 98, in whichthe axle journals 92 are accommodated. The planet carrier 98 is in turnmounted in an intermediate bearing 101 and a sliding bearing 104 whichis arranged therein. The intermediate bearing 101 is configured in theform of a pot in such a way that both the planet carrier 98 and theplanet gears 86 are accommodated in said intermediate bearing.Furthermore, the hollow wheel 95 is arranged in the pot-shapedintermediate bearing 101 and is ultimately closed by a cover 107 withrespect to the armature 37. The intermediate bearing 101 is alsosupported by way of its outer circumference on the inner face of thepole tube 28. The armature 37 has a further shaft journal 110 on thatend of the drive shaft 44 which is remote from the commutator 52, saidshaft journal likewise being accommodated in a sliding bearing 113. Thesliding bearing 113 is in turn accommodated in a central bore in theplanet carrier 98. The planet carrier 98 is integrally connected to theoutput drive shaft 116. This output drive shaft 116 is supported by itsend 119 which is remote from the intermediate bearing 101 in a furtherbearing 122, the A bearing, which is formed in the drive end plate 19.The output drive shaft 116 is divided into various sections: a sectionwith a straight gearing 125 (inner gearing) which is part of a shaft-hubconnection 128 thus follows the section which is arranged in the slidingbearing 104 of the intermediate bearing 101. This shaft-hub connection128 makes it possible in this case for a driver 131 to perform anaxially linear sliding movement. This driver 131 is a sleeve-likeprotrusion, which is integral with a pot-shaped outer ring 132 of thefreewheel 137. This freewheel 137 (ratchet) furthermore comprises theinner ring 140, which is arranged radially within the outer ring 132.Clamping bodies 138 are arranged between the inner ring 140 and theouter ring 132. The clamping bodies 138, in interaction with the innerand the outer ring, prevent a relative movement between the outer ringand the inner ring in a second direction. The freewheel 137 allows arelative movement between the inner ring 140 and the outer ring 132 inonly one direction. In this exemplary embodiment, the inner ring 140 isintegrally formed with the starter pinion 22 and the helical gearing 143(outer helical gearing) thereof.

The relay 16 has a pin 150, which constitutes an electrical contact andis connected to the positive terminal of an electrical starter battery(not illustrated in FIG. 1). This pin 150 is passed through a relaycover 153. This relay cover 153 closes off a relay housing 156, which isfastened to the drive end plate 19 by means of a plurality of fasteningelements 159 (screws). A pull-in winding 162 and a holding winding 165are furthermore arranged in the relay 16. The pull-in winding 162 andthe holding winding 165 both each induce an electromagnetic field in theswitched-on state, said electromagnetic field flowing through both therelay housing 156 (composed of electromagnetically conductive material),a linearly moving armature 168 and an armature return 171. The armature168 has a push rod 174, which is moved in the direction of a switchingpin 177 during linear pull-in of the armature 168. With this movement ofthe push rod 174 toward the switching pin 177, said switching pin ismoved out of its rest position in the direction toward two contacts 180and 181, so that a contact bridge 184, which is fitted at the end of theswitching pin 177, electrically connects the two contacts 180 and 181 toone another. As a result, electrical power is passed from the pin 150,beyond the contact bridge 184, to the power supply line 61 and thereforeto the carbon brushes 58. Power is supplied to the starter motor 13 inthe process.

However, the relay 16 and the armature 168 furthermore also have thetask of moving, with a pull element 187, a lever which is arranged inthe drive end plate 19 such that it can rotate. The lever 190, usuallyin the form of a forked lever, engages with two “prongs” (not shownhere) on its outer circumference around two disks 193 and 194 in orderto move a driver ring 197, which is trapped between said disks, towardthe freewheel 137 counter to the resistance of the spring 200 andthereby to mesh the starter pinion 22 with the ring gear 25 of theinternal combustion engine.

FIG. 2 shows a schematic section through the relay for operating thestarting apparatus according to FIG. 1 on an enlarged scale.

The illustration according to FIG. 2 shows a relay for operating anelectrical starting apparatus on an enlarged scale.

FIG. 2 shows that the relay 16 has a linearly moving armature, that isto say a relay armature 168, the end face 206 of said armaturecorresponding to the end face of the armature return 171 which isaccommodated in the relay housing 156. A hollow space 236, which isfilled with a fluid, for example air, is formed between the end face 206and that end face of the armature return 171 which is situated oppositesaid end face 206. A channel 204 which issues at a mouth 208 in the endface 206 of the relay armature 168 passes through the relay armature.

A channel 210 likewise passes through the armature return 171, a valve,which is illustrated on an enlarged scale in FIG. 3, for example in theform of a non-return valve 212, being accommodated in said channel.

Both the channel 204 in the relay armature 168 and the channel 210 inthe armature return 171 have a diameter of only a few mm. The channel204 in the relay armature 168 extends from the mouth 208, runs throughthe relay armature 168, and issues in the external area surrounding therelay 16.

The channel 210, which passes through the armature return 171, connectsthe hollow space 236 to a relief space 253 on that side of the armaturereturn 171 which is averted from the relay armature 168 and isaccommodated in the relay housing 156 of the relay 16 in a stationarymanner. Reference symbol 153 denotes a relay cover of the relay 16.

FIG. 3 shows a valve which is in the form of a non-return valve 212 andis arranged in the channel 210 of the armature return 171. Aspring-loaded, in this case spherical, closing element 214 is providedin the valve 212 which is in the form of a non-return valve, saidclosing element being pushed by the spring into a seat 216 which isformed in the armature return 171. Both a main channel 218, which has afirst diameter D₁, compare reference symbol 220, and an auxiliarychannel 220, which has a smaller, second diameter D₂, compare item 224,extend from the seat 216 of the valve 212. While the main channel 218 isclosed when the closing element 214 is in its seat 216, this is not thecase for the auxiliary channel 220 which is still permeable but has asecond, smaller diameter D₂, compare item 224, than the first diameterD₁, compare item 222 of the main channel 218, in the closed state of theclosing element 214.

In the variant embodiment of a pneumatic damping arrangement illustratedin FIGS. 2 and 3, the volume of fluid which is contained in the hollowspace 236 is compressed as the end surface 206 approaches in the eventof a linear movement of the relay armature 168 in the direction of theend face of the armature return 171. As a result, the energy of therelay armature 168 which is moving toward the armature return 171 isreduced. On account of the build-up of pressure, the non-return valve212 closes the seat 216 and therefore the main channel 218, while a flowof fluid through the auxiliary channel 200, which is not closed by theclosing element 214 and issues into the relief space 253, can bereduced. This results in a gradual reduction in pressure in the hollowspace 236, with the pressure level, however, being kept at a level suchthat the end surface 206 of the relay armature which is moving towardthe armature return 171 does not come to a hard stop and the developmentof noise due to hard contact between the metals of the end surface 206at that end surface of the relay armature 171 which corresponds to saidend surface 206 is precluded.

The illustration according to FIG. 4 shows that hydraulic damping canalso be achieved by a guide bush, which is accommodated on the switchingpin 177, in this variant embodiment.

In this variant embodiment, compare the illustration according to FIG.1, the guide bush 202, which is accommodated on the switching pin 177,is provided with a number of openings 230 and 232 which can be in theform of, for example, transverse bores which run through the wall of theguide bush 202.

In the illustration according to FIG. 4, the guide bush 202 havingopenings, which are in the form of transverse bores 230 and 232, isplaced in a first position 226 which is indicated by solid lines. If, asshown in the illustration according to FIG. 2, the relay armature 168moves by way of its end face 206 into the hollow space 236 in the relayhousing 156 of the relay 16, the volume of fluid present in said hollowspace will be compressed. The switching pin 177, which is notillustrated in FIG. 2 but is illustrated in FIG. 1, moves into thearmature return 171, so that the guide bush 202 which is accommodated onsaid switching pin is moved from the first position 226, which isillustrated in FIG. 4 and indicated by solid lines, to its secondposition 228, which is indicated by dashed lines. During this movementinto the relief space 253, the openings 230 in the wall of the guidebush 202 are fully or partially exposed, so that a connection is createdbetween the hollow space 236 and the relief space 256 within the relayhousing 156. Depending on the design of the cross sections and thenumber of openings in the wall of the guide bush 202, compressed fluidflows out of the hollow space 236 and into the relief space 253. Thecontact between the end face 206 of the relay armature 168 and the endface of the armature return 171 is pneumatically damped by virtue ofthis gradual reduction in pressure in the hollow space 236 and by virtueof compressed fluid flowing out of the hollow space 236 and into therelief space 253 in a controlled manner.

The illustration according to FIG. 5 shows a further variant embodimentof a pneumatic damping arrangement of a relay.

In this variant embodiment, the armature 168, which is only indicated inFIG. 5, is provided with a circumferential slot 238 or a recess over itscircumference. In the illustration according to FIG. 5, thecircumferential slot 238 is approximately square and has a V lip 240arranged in it.

The V lip 240 has a limb which engages against the wall of the relayhousing 156. If the relay armature 168 moves in the second movementdirection 244, the upper limb of the V lip 240 will engage against thewall of the relay housing 156, so that damping in respect of the relayarmature 168 is provided in a manner dependent on the movementdirection. If, in contrast, the relay armature 168 is moved in the firstmovement direction 242, the volume of fluid enclosed in the hollow space236 will be relieved of pressure.

The variant embodiments of a pneumatic damping arrangement according toFIGS. 2, 3 4 and 5 can be used to provide direction-dependent pneumaticdamping if the relay armature 168 moves, by way of its end face 206,into the hollow space 236, the volume of fluid which is contained insaid hollow space is compressed, and a gradual reduction in pressure isinitiated in the hollow space 236 or, compare the illustration accordingto FIG. 5, the hollow space 236 is sealed off from pressure loss, sothat the development of noise when the end face 206 of the relayarmature 168 stops against that end face of the armature return 171which is accommodated in the relay housing 156 in a stationary manner issignificantly damped.

The illustrations according to FIGS. 6 and 6.1 show a further variantembodiment of the pneumatic damping arrangement proposed according tothe invention.

If the end face 206 of the armature 168 has reached a distance Δs fromthe end face of the armature return 171, a valve element 246 isoperated. The valve element 246, which is in the form of a peg in thiscase and which is accommodated in a channel 254 such that it can move,is operated by a valve stop 250 stopping against the end of the peg-likevalve element 246. A head 252 of the valve element 246 is moved into therelief space 253 against the action of the spring force of the valvespring 248, so that a slot 256 is exposed, volumes of fluid flowing outof the hollow space 236 which is defined by the distance Δs and into therelief space 253 via said slot.

The valve which is illustrated in the illustration according to FIG. 6responds only when a well-defined distance Δs between the end face 206of the relay armature 168 and the end face of the armature return 171,which is designed to have a geometry which corresponds to said end faceof the relay armature, is reached.

For the sake of completeness, it should be mentioned that referencesymbol 150 denotes the pin by means of which power is supplied to therelay 16.

The illustration according to FIG. 6 shows that the slot 256 in thearmature return 171 runs, for example, above the actual channel 254 inthe material of the armature return 171. The slot 256 can also be formedat the 3 o'clock, 6 o'clock or 9 o'clock position or any other desireddefined position in respect of the illustration according to FIG. 6.1.

The valve element 246 which is illustrated in the illustration accordingto FIG. 6 opens only when a well-defined distance Δs between thecomponents relay armature 168 and the armature return 171, which isarranged in the relay housing 156 in a stationary manner, is reached.

1. A relay (16), having a relay armature (168) and an armature return(171), characterized in that a volume of fluid, which is enclosed in ahollow space (236, Δs), between the relay armature (168) and thearmature return (171) pneumatically damps the movement of the relayarmature (168) in the direction of the armature return (171).
 2. Therelay (16) as claimed in claim 1, characterized in that the relayarmature (168) has, in a circumference of the armature, a dampingelement (240) which is operated in a manner dependent on a movementdirection.
 3. The relay (16) as claimed in claim 1, characterized inthat a valve (212), which is acted on in a closing direction bycompression of the fluid in the hollow space (236), is located in one ofthe armature return (171) and the relay armature (168).
 4. The relay(16) as claimed in claim 3, characterized in that the hollow space (236,Δs) is relieved of pressure by an auxiliary channel (220) when the valve(212) is closed.
 5. The relay (16) as claimed in claim 3, characterizedin that the hollow space (236, Δs) is refilled with fluid by a mainchannel (218) and an auxiliary channel (220), which both issue into aseat (216) of the valve (212), when the valve (212) is open.
 6. Therelay (16) as claimed in claim 1, characterized in that the hollow space(236, Δs) is configured to be relieved of pressure by a guide bush (202)having at least one opening (230, 232).
 7. The relay (16) as claimed inclaim 1, characterized in that a valve element (246) which relieves thehollow space (236) of pressure is operated when a distance Δs betweenthe relay armature (168) and the armature return (171) is reached. 8.The relay (16) as claimed in claim 7, characterized in that the valveelement (246) is located in the armature return (171).
 9. The relay (16)as claimed in claims 7, characterized in that the armature return (171)comprises a channel (254) in which the valve element (246) is guided,and also a slot (256) which issues into a relief space (253).
 10. Therelay (16) as claimed in claim 1, characterized in that the pneumaticdamping is damping, which is dependent on the movement direction, inrespect of the relay armature (168) approaching the armature return(171).
 11. The relay (16) as claimed in claim 1, characterized in thatat least one of the relay armature (168) and the armature return (171)has a channel (204, 210) for throttled deaeration of the hollow space(236).
 12. The relay (16) as claimed in claim 1, characterized in that asealing element (240), between the relay armature (168) and the relayhousing (156) seals off the hollow space (236).
 13. The relay (16) asclaimed in claim 1, characterized in that the relay is for electricalstarter apparatuses for internal combustion engines.
 14. The relay (16)as claimed in claim 3, characterized in that the valve (212) is anon-return valve.
 15. The relay (16) as claimed in claim 12,characterized in that the sealing element (240) is a sealing lip or asealing ring.